01a4eab602a3a72d216d71ed91829bd63459e136
[sfrench/cifs-2.6.git] / fs / btrfs / zstd.c
1 /*
2  * Copyright (c) 2016-present, Facebook, Inc.
3  * All rights reserved.
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public
7  * License v2 as published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12  * General Public License for more details.
13  */
14 #include <linux/bio.h>
15 #include <linux/err.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/mm.h>
19 #include <linux/pagemap.h>
20 #include <linux/refcount.h>
21 #include <linux/sched.h>
22 #include <linux/slab.h>
23 #include <linux/zstd.h>
24 #include "compression.h"
25
26 #define ZSTD_BTRFS_MAX_WINDOWLOG 17
27 #define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
28 #define ZSTD_BTRFS_DEFAULT_LEVEL 3
29
30 static ZSTD_parameters zstd_get_btrfs_parameters(size_t src_len)
31 {
32         ZSTD_parameters params = ZSTD_getParams(ZSTD_BTRFS_DEFAULT_LEVEL,
33                                                 src_len, 0);
34
35         if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG)
36                 params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG;
37         WARN_ON(src_len > ZSTD_BTRFS_MAX_INPUT);
38         return params;
39 }
40
41 struct workspace {
42         void *mem;
43         size_t size;
44         char *buf;
45         struct list_head list;
46         ZSTD_inBuffer in_buf;
47         ZSTD_outBuffer out_buf;
48 };
49
50 static void zstd_free_workspace(struct list_head *ws)
51 {
52         struct workspace *workspace = list_entry(ws, struct workspace, list);
53
54         kvfree(workspace->mem);
55         kfree(workspace->buf);
56         kfree(workspace);
57 }
58
59 static struct list_head *zstd_alloc_workspace(void)
60 {
61         ZSTD_parameters params =
62                         zstd_get_btrfs_parameters(ZSTD_BTRFS_MAX_INPUT);
63         struct workspace *workspace;
64
65         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
66         if (!workspace)
67                 return ERR_PTR(-ENOMEM);
68
69         workspace->size = max_t(size_t,
70                         ZSTD_CStreamWorkspaceBound(params.cParams),
71                         ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
72         workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
73         workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
74         if (!workspace->mem || !workspace->buf)
75                 goto fail;
76
77         INIT_LIST_HEAD(&workspace->list);
78
79         return &workspace->list;
80 fail:
81         zstd_free_workspace(&workspace->list);
82         return ERR_PTR(-ENOMEM);
83 }
84
85 static int zstd_compress_pages(struct list_head *ws,
86                 struct address_space *mapping,
87                 u64 start,
88                 struct page **pages,
89                 unsigned long *out_pages,
90                 unsigned long *total_in,
91                 unsigned long *total_out)
92 {
93         struct workspace *workspace = list_entry(ws, struct workspace, list);
94         ZSTD_CStream *stream;
95         int ret = 0;
96         int nr_pages = 0;
97         struct page *in_page = NULL;  /* The current page to read */
98         struct page *out_page = NULL; /* The current page to write to */
99         unsigned long tot_in = 0;
100         unsigned long tot_out = 0;
101         unsigned long len = *total_out;
102         const unsigned long nr_dest_pages = *out_pages;
103         unsigned long max_out = nr_dest_pages * PAGE_SIZE;
104         ZSTD_parameters params = zstd_get_btrfs_parameters(len);
105
106         *out_pages = 0;
107         *total_out = 0;
108         *total_in = 0;
109
110         /* Initialize the stream */
111         stream = ZSTD_initCStream(params, len, workspace->mem,
112                         workspace->size);
113         if (!stream) {
114                 pr_warn("BTRFS: ZSTD_initCStream failed\n");
115                 ret = -EIO;
116                 goto out;
117         }
118
119         /* map in the first page of input data */
120         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
121         workspace->in_buf.src = kmap(in_page);
122         workspace->in_buf.pos = 0;
123         workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
124
125
126         /* Allocate and map in the output buffer */
127         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
128         if (out_page == NULL) {
129                 ret = -ENOMEM;
130                 goto out;
131         }
132         pages[nr_pages++] = out_page;
133         workspace->out_buf.dst = kmap(out_page);
134         workspace->out_buf.pos = 0;
135         workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
136
137         while (1) {
138                 size_t ret2;
139
140                 ret2 = ZSTD_compressStream(stream, &workspace->out_buf,
141                                 &workspace->in_buf);
142                 if (ZSTD_isError(ret2)) {
143                         pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
144                                         ZSTD_getErrorCode(ret2));
145                         ret = -EIO;
146                         goto out;
147                 }
148
149                 /* Check to see if we are making it bigger */
150                 if (tot_in + workspace->in_buf.pos > 8192 &&
151                                 tot_in + workspace->in_buf.pos <
152                                 tot_out + workspace->out_buf.pos) {
153                         ret = -E2BIG;
154                         goto out;
155                 }
156
157                 /* We've reached the end of our output range */
158                 if (workspace->out_buf.pos >= max_out) {
159                         tot_out += workspace->out_buf.pos;
160                         ret = -E2BIG;
161                         goto out;
162                 }
163
164                 /* Check if we need more output space */
165                 if (workspace->out_buf.pos == workspace->out_buf.size) {
166                         tot_out += PAGE_SIZE;
167                         max_out -= PAGE_SIZE;
168                         kunmap(out_page);
169                         if (nr_pages == nr_dest_pages) {
170                                 out_page = NULL;
171                                 ret = -E2BIG;
172                                 goto out;
173                         }
174                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
175                         if (out_page == NULL) {
176                                 ret = -ENOMEM;
177                                 goto out;
178                         }
179                         pages[nr_pages++] = out_page;
180                         workspace->out_buf.dst = kmap(out_page);
181                         workspace->out_buf.pos = 0;
182                         workspace->out_buf.size = min_t(size_t, max_out,
183                                                         PAGE_SIZE);
184                 }
185
186                 /* We've reached the end of the input */
187                 if (workspace->in_buf.pos >= len) {
188                         tot_in += workspace->in_buf.pos;
189                         break;
190                 }
191
192                 /* Check if we need more input */
193                 if (workspace->in_buf.pos == workspace->in_buf.size) {
194                         tot_in += PAGE_SIZE;
195                         kunmap(in_page);
196                         put_page(in_page);
197
198                         start += PAGE_SIZE;
199                         len -= PAGE_SIZE;
200                         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
201                         workspace->in_buf.src = kmap(in_page);
202                         workspace->in_buf.pos = 0;
203                         workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
204                 }
205         }
206         while (1) {
207                 size_t ret2;
208
209                 ret2 = ZSTD_endStream(stream, &workspace->out_buf);
210                 if (ZSTD_isError(ret2)) {
211                         pr_debug("BTRFS: ZSTD_endStream returned %d\n",
212                                         ZSTD_getErrorCode(ret2));
213                         ret = -EIO;
214                         goto out;
215                 }
216                 if (ret2 == 0) {
217                         tot_out += workspace->out_buf.pos;
218                         break;
219                 }
220                 if (workspace->out_buf.pos >= max_out) {
221                         tot_out += workspace->out_buf.pos;
222                         ret = -E2BIG;
223                         goto out;
224                 }
225
226                 tot_out += PAGE_SIZE;
227                 max_out -= PAGE_SIZE;
228                 kunmap(out_page);
229                 if (nr_pages == nr_dest_pages) {
230                         out_page = NULL;
231                         ret = -E2BIG;
232                         goto out;
233                 }
234                 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
235                 if (out_page == NULL) {
236                         ret = -ENOMEM;
237                         goto out;
238                 }
239                 pages[nr_pages++] = out_page;
240                 workspace->out_buf.dst = kmap(out_page);
241                 workspace->out_buf.pos = 0;
242                 workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
243         }
244
245         if (tot_out >= tot_in) {
246                 ret = -E2BIG;
247                 goto out;
248         }
249
250         ret = 0;
251         *total_in = tot_in;
252         *total_out = tot_out;
253 out:
254         *out_pages = nr_pages;
255         /* Cleanup */
256         if (in_page) {
257                 kunmap(in_page);
258                 put_page(in_page);
259         }
260         if (out_page)
261                 kunmap(out_page);
262         return ret;
263 }
264
265 static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
266 {
267         struct workspace *workspace = list_entry(ws, struct workspace, list);
268         struct page **pages_in = cb->compressed_pages;
269         u64 disk_start = cb->start;
270         struct bio *orig_bio = cb->orig_bio;
271         size_t srclen = cb->compressed_len;
272         ZSTD_DStream *stream;
273         int ret = 0;
274         unsigned long page_in_index = 0;
275         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
276         unsigned long buf_start;
277         unsigned long total_out = 0;
278
279         stream = ZSTD_initDStream(
280                         ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
281         if (!stream) {
282                 pr_debug("BTRFS: ZSTD_initDStream failed\n");
283                 ret = -EIO;
284                 goto done;
285         }
286
287         workspace->in_buf.src = kmap(pages_in[page_in_index]);
288         workspace->in_buf.pos = 0;
289         workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
290
291         workspace->out_buf.dst = workspace->buf;
292         workspace->out_buf.pos = 0;
293         workspace->out_buf.size = PAGE_SIZE;
294
295         while (1) {
296                 size_t ret2;
297
298                 ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
299                                 &workspace->in_buf);
300                 if (ZSTD_isError(ret2)) {
301                         pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
302                                         ZSTD_getErrorCode(ret2));
303                         ret = -EIO;
304                         goto done;
305                 }
306                 buf_start = total_out;
307                 total_out += workspace->out_buf.pos;
308                 workspace->out_buf.pos = 0;
309
310                 ret = btrfs_decompress_buf2page(workspace->out_buf.dst,
311                                 buf_start, total_out, disk_start, orig_bio);
312                 if (ret == 0)
313                         break;
314
315                 if (workspace->in_buf.pos >= srclen)
316                         break;
317
318                 /* Check if we've hit the end of a frame */
319                 if (ret2 == 0)
320                         break;
321
322                 if (workspace->in_buf.pos == workspace->in_buf.size) {
323                         kunmap(pages_in[page_in_index++]);
324                         if (page_in_index >= total_pages_in) {
325                                 workspace->in_buf.src = NULL;
326                                 ret = -EIO;
327                                 goto done;
328                         }
329                         srclen -= PAGE_SIZE;
330                         workspace->in_buf.src = kmap(pages_in[page_in_index]);
331                         workspace->in_buf.pos = 0;
332                         workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
333                 }
334         }
335         ret = 0;
336         zero_fill_bio(orig_bio);
337 done:
338         if (workspace->in_buf.src)
339                 kunmap(pages_in[page_in_index]);
340         return ret;
341 }
342
343 static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
344                 struct page *dest_page,
345                 unsigned long start_byte,
346                 size_t srclen, size_t destlen)
347 {
348         struct workspace *workspace = list_entry(ws, struct workspace, list);
349         ZSTD_DStream *stream;
350         int ret = 0;
351         size_t ret2;
352         unsigned long total_out = 0;
353         unsigned long pg_offset = 0;
354         char *kaddr;
355
356         stream = ZSTD_initDStream(
357                         ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
358         if (!stream) {
359                 pr_warn("BTRFS: ZSTD_initDStream failed\n");
360                 ret = -EIO;
361                 goto finish;
362         }
363
364         destlen = min_t(size_t, destlen, PAGE_SIZE);
365
366         workspace->in_buf.src = data_in;
367         workspace->in_buf.pos = 0;
368         workspace->in_buf.size = srclen;
369
370         workspace->out_buf.dst = workspace->buf;
371         workspace->out_buf.pos = 0;
372         workspace->out_buf.size = PAGE_SIZE;
373
374         ret2 = 1;
375         while (pg_offset < destlen
376                && workspace->in_buf.pos < workspace->in_buf.size) {
377                 unsigned long buf_start;
378                 unsigned long buf_offset;
379                 unsigned long bytes;
380
381                 /* Check if the frame is over and we still need more input */
382                 if (ret2 == 0) {
383                         pr_debug("BTRFS: ZSTD_decompressStream ended early\n");
384                         ret = -EIO;
385                         goto finish;
386                 }
387                 ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
388                                 &workspace->in_buf);
389                 if (ZSTD_isError(ret2)) {
390                         pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
391                                         ZSTD_getErrorCode(ret2));
392                         ret = -EIO;
393                         goto finish;
394                 }
395
396                 buf_start = total_out;
397                 total_out += workspace->out_buf.pos;
398                 workspace->out_buf.pos = 0;
399
400                 if (total_out <= start_byte)
401                         continue;
402
403                 if (total_out > start_byte && buf_start < start_byte)
404                         buf_offset = start_byte - buf_start;
405                 else
406                         buf_offset = 0;
407
408                 bytes = min_t(unsigned long, destlen - pg_offset,
409                                 workspace->out_buf.size - buf_offset);
410
411                 kaddr = kmap_atomic(dest_page);
412                 memcpy(kaddr + pg_offset, workspace->out_buf.dst + buf_offset,
413                                 bytes);
414                 kunmap_atomic(kaddr);
415
416                 pg_offset += bytes;
417         }
418         ret = 0;
419 finish:
420         if (pg_offset < destlen) {
421                 kaddr = kmap_atomic(dest_page);
422                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
423                 kunmap_atomic(kaddr);
424         }
425         return ret;
426 }
427
428 static void zstd_set_level(struct list_head *ws, unsigned int type)
429 {
430 }
431
432 const struct btrfs_compress_op btrfs_zstd_compress = {
433         .alloc_workspace = zstd_alloc_workspace,
434         .free_workspace = zstd_free_workspace,
435         .compress_pages = zstd_compress_pages,
436         .decompress_bio = zstd_decompress_bio,
437         .decompress = zstd_decompress,
438         .set_level = zstd_set_level,
439 };